Needle bar for sewing machine



Nov. 29, 1955 w. A. AYRES 2,725,024

NEEDLE BAR FOR SEWING MACHINE Filed April 16, 1952 j INVENTOR.

Madam MR A. fiykes %rramv ys United States Patent 0 NEEDLE BAR F011 SEWING MACHINE Waldemar A. Ayrcs, Lakewood, Ohio, :assignorto White Sewing Machine Corporation, Lakewood, Ohio, a corporation of Delaware Application April 16, 1-952, Serial No. 282,591

1 Claim. (Cl. 112-218) This invention relates to an improved and'novel needle bar for a sewing machine. The present day power operated sewing machine functions at relatively high operating speed and there have been efiorts made to increase the operating speed of the machine but such efforts commonly result in the creation of undesirable factors.

One of the chief deterrents to high speed operation of a sewing machine is the excessive vibration created by the moving parts of the machine, and particularly by the rapidly reciprocating needle bar which is of substantial mass and must change its direction of movement at exceedingly short intervals.

An object of the invention is to provide an improved and novel needle bar for a sewing machine and which needle bar may be reciprocated at high speeds without creating objectionable vibrations.

Another object is to provide a needle bar as specified in the above object and wherein the mass of the bar is at a minimum but at the same time the bar has the requisite strength and wearing surface hardness to -adequately withstand the strains and wear to which it is subjected.

Further and additional objects and advantages will become apparent hereinafter during the detailed description of an embodiment of the invention which is to follow.

It is proposed to provide a needle bar of tubular or hollow cross section substantially throughout its length to minimize its mass but of the necessary wall thickness .to provide the required strength. The :tubular'needle bar is formed of light weight material vas,'for instance,.-a .nonferrous metal such as magnesium, aluminum .or the like.

The tubular needle bar is provided on its surface with a hard wear-resistant skin as for example it can beplated with a hard metal plating such' as chromium or other suitable coating or it can'be coated by spraying a"h a'rd metal coating thereon, such as a molybdenum steel coating,

and then grinding the sprayed rod to size. It will thus be seen that the needle bar is light in weight while possessing high strength and great wearing quality.

In addition, it is proposed to operatively connect the needle bar with the crank pin that drives the same by means of a crank arm preferably formed of the same material as the needle bar and provided at one end with a hardened bearing sleeve which pivotally receives a hardened pin carried by the needle bar and at its other end with a hub portion containing a suitable bearing in which moves the crank pin that drives the needle bar.

Referring to the accompanying drawing illustrating an embodiment of the invention and forming part of this specification,

Fig. 1 is an end view of the end face of the sewing machine head and of a portion of the sewing machine bed with the closure plate of the end face removed to show the needle bar in elevation and the bearing in which the needle bar slides partly in elevation and partly in section, a fragment of the presser foot also being indicated.

2,725,024 Patented Nov. 29, 1955 Fig. 2 is a detached elevational view of the needle bar and crank arm shown in Fig. 1.

Fig. 3 is takenlooking at the needle bar from the right hand side of Fig. 2, the needle bar being shown in elevation as is also a portion of the main drive shaft, the crank disk and crankpin while the crank arm is shown in section, and

Fig. 4 is a sectional view on an enlarged scale and is taken substantially on line 44 of Fig. 2 looking in the direction of the arrows.

Referring first to Fig. 1, the end face portion of the sewing machine head with the cover plate removed is indicated at 10 while the main shaft 11 of the sewing machine is rotatablysupported in suitable bearings in the horizontal arm of the head, said bearings not being shown as they are Well understood in the art.

The main shaft 11 has fixed or secured thereto a crank disk 12 which mounts an eccentric crank pin 13 that drives the needle bar in its reciprocating movement as-will later be explained. The disk 12 is balanced for the 'weight of the pin 13 by beingprovided with balancing openings 12a. The usual presser foot 14 is indicated in Fig. 1 and said presser'foot is connected to the presser foot rod 15 which moves verticallyyin the end face 10 as willbe well understood in the art.

The end face 10 in its lower wall is provided with a bearing opening which aligns with the opening through an upstanding bearing boss 16 and there is a suitable oil bearing 17 mounted in the 'boss and the opening and Within which bearing theneedlebar now to be described is slidably mounted.

The needle bar is in the form of a rod and is produced from one of the light metals, such as one of the nonferrous metals like magnesium, aluminum or the like. The rod 18 from which the needle 'bar is formed may be drilled or otherwise formed to give it'a hollow interior 19 which extends from the lower or needle carrying end of the bar to closely adjacent the upper end thereof, that is to a point such as indicated at 19a. The hollow or tubular rod 18 formedfrom the light weight material such as one of the non-ferrous metals like magnesium, aluminum or the like is provided with ahard thin wearresistant surface skin. This skin 'may be'provided in any suitable Way, but-preferably it is'accomp'lished by plating the exterior of the rod with a hard'metallic plating coating as indicated at 20, and such coating may be chromium plating, or it maybe a hard-metal sprayed coating such as molybdenum steel, many other suitable metallic coating having the requisite wear-resistant hardness to withstand the rapid reciprocat'ing'movement of the needle bar in the bearing '17.

It will be understood that the wear-resistant skin or plated coating 20 is very thin compared to the wall thickness of the tubular rod and that the relative thicknesses of the rod and coating as indicated in Fig. 4 do not represent the actual thickness ratio.

The needle bar above the point 19:: at which its tubular or hollow formation terminates is bifurcated and mounts a hardened metal pin 21 which may be a hardened steel pin or other suitable hardened pin, it being understood that said pin is mounted in aligned openings in the arms 22 and 23 forming the bifurcated upper end of the needle bar.

The lower end of the needle bar has fixed therein a plug 24 which is provided with a socket that receives the needle 25. The lower end of the needle bar also mounts exteriorly a clamping screw bracket 26 that extends laterally of the needle bar in the form of a reduced portion of the bracket and that the latter portion is provided with a threaded bore aligning with an opening in the plug 24 communicating with the socket therein so that a clamping screw 27 can be screwed inwardly and outwardly of the threaded bore and the opening to clamp the needle 25 in the socket or to release the same for removal from the socket.

The clamping screw 27 is provided on its outer end with a relatively large head or knob 27a to facilitate its operation. The reduced laterally extending portion of the bracket 26 also serves as a convenient mounting sup- ,port for attachments as will be well understood in the art.

The needle bar is operatively connected to the crank pin 13 by means of a crank arm 28 which preferably is formed of light metal, such as a non-ferrous metal like magnesium, aluminum or the like. The lower end of the crank arm 28 extends between the arms 22 and 23 of the bifurcated upper end of the needle bar and is provided with an opening in which is mounted a hardened bearing sleeve 29 that receives the hardened pin 21, said bearing sleeve being a steel sleeve 01' any other suitable hardened sleeve. The upper end of the crank arm 28 is provided with a hub 30 and is severed or slit longitudinally as indicated at 31, said slit extending from the hub 30. A suitable slit bearing sleeve 32 such as a porous bronze bearing sleeve is mounted in the hub 30 and receives the crank pin 13. Then because of the slit 31 the hub 30 and bearing 32 can be adjusted on the pin 13 by the adjusting screw 33 carried by the arm 28 and extending transversely of the slit 31 and acting when tightened to draw the opposite sides of the slit together as will be well understood in the art.

It will be seen that as the shaft 11 rotates the crank pin 13 operating through the crank arm 28 will cause the needle bar to reciprocate in the bearing 17. Inasmuch as the needle bar is extremely light in weight as is also the crank arm 28, the shaft 11 can be driven at very high speeds to efifect extremely rapid reciprocation of the needle bar and substantially negligible vibrations will be created by such reciprocation of the needle bar. This minimum of vibration results directly from the low weight of the needle bar and the fact that its frequently recurring changes in direction of movement involve the successive deceleration, stopping and acceleration of a relatively light mass.

The needle bar attains its lightness in weight partly because of the material of which it is constructed, and, in addition, because of its hollow or tubular formation and at the same time such hollow or tubular formation imparts requisite strength to the needle bar at any crosssectional location. The hard wear-resistant exterior skin of the needle bar also provides the requisite Wear-resistant qualities to enable the needle bar to be rapidly reciprocated in the bearing 17.

The operative interconnection between the upper end of the needle bar and the crank arm 28 being accomplished by the steel pin 21 and the hardened bearing sleeve 29 provides for the desired and required wearing qualities at this location. In addition, the bearing 32 4 carried by the hub 30 and into which the crank pin 13 extends likewise provides the necessary Wear-resistant characteristics at this location.

In view of the above it will be seen that the needle bar embodying the invention attains in an adequate manner the objectives and advantages hereinbefore referred to. It has been found by using a needle bar of this construction that the sewing machine can be operated at extremely high speeds and due to the light mass of the needle bar the vibrations are reduced to a minimum and, in fact, are substantially eliminated.

Although a preferred embodiment of the invention has been illustrated and described herein it will be understood that the invention is susceptible of various modifications and adaptations within the scope of the appended claim.

Having thus described my invention, I claim:

A needle bar mechanism comprising a rod provided with a longitudinal bore extending substantially the length of the rod from one end thereof but terminating short of the opposite end thereof whereby said bore is closed at its terminating end, said bore having a diameter such as to provide a relatively large diameter chamber within the rod as compared to the total diameter of the rod, said rod at its said opposite end beyond the terminating end of the bore being provided with spaced parallel arms having aligned openings therein, a pin mounted in said openings, a plug mounted in and closing the bore at said one end of the rod and provided with a needle receiving socket, said rod being formed of non-ferrous light weight metal and provided on its exterior with a covering skin of different material and relatively thin as compared to the wall thickness of the chamber provided in said rod by said bore, said skin being of a different material than said rod and possessing greater wear resistant characteristics than those of the rod, a non-ferrous light weight metal crank arm extending between the parallel arms at the said opposite end of said rod and provided with a bearing sleeve receiving the pin carried by said parallel arms and interconnecting the crank arm to said rod on the longitudinal center line of the latter, the opposite end of said crank arm being provided with a hub, and a bearing sleeve mounted in said hub and adapted to receive a crank pin carried by a needle bar driving member.

References Cited in the file of this patent UNITED STATES PATENTS 478,576 Diehl July 12, 1892 1,020,057 Ringe Mar. 12, 1912 1,697,424 Greenwood Jan. 1, 1W9 1,836,760 Konchan Dec. 15, 1931 2,005,673 Eames June 18, 1935 2,138,981 Peters Dec. 6. 1938 2,364,740 Menking Dec. 12, 1944 2,599,226 Briem June 3, 1952 

